23 posts in this topic

Still Waters 21,365

How did some dinosaurs reach such soaring heights -- up to 100 feet high in some cases? Efficient lungs and respiration, along with egg laying, might have given dinos a growth edge when compared to other animals, suggests new research.

The study also negates a popular theory that animals tended to become bigger over the course of their evolution.

While some dinosaurs grew ever larger over subsequent generations, not all did.

I've heard that it might be possible that the earth's atmosphere was slightly different, and that might have led to larger animals. Not sure if this has ever been verified at all though.

The atmosphere contained a lot more oxygen (about 20% more I think) which allowed insects to get to very large sizes, like dragonflies with 3ft wingspans etc. This was due to how insects breath through their skin, which is totally different to animals. As the oxygen levels decreased to what they are today, the insects became smaller and smaller.

I suppose more oxygen may have helped the dinosaurs in some way but not sure about growth. Maybe it gave them more stamina, which in turn allowed muscle to form more easily followed by larger bones to support the extra muscle?, Just a thought. I am no expert on these matters

Share this post

Link to post

Share on other sites

Munkh 0

I had heard once that the air pressure may have been higher as well as more oxygen in the air. This would allow blood and other body fluids to be pumped the long distance to the extremities including the heads of some of these beasts. This also may have allowed for easier flight of the winged Dino's

Share this post

Link to post

Share on other sites

Mr Supertypo 162

could that be because of alimentation? ancient plans had a low nutritional value. That means herbivores had to eat more to gain some valuable nutrient. With time they growt huge (look at sauropods, huge bellis and small heads)and carnivores followed to mach in size the giant herbivores.

Share this post

Link to post

Share on other sites

Junior Chubb 6,323

Interesting article, but we may never get the answers. This is like asking why some fish are small and some fish are large yet they all live in water. Evolution, environment and competition causes these size differences and these parameters will be unique for each animal (dinosaur) on the planet.

Abramelin 2,499

The article also tries to explain why mammals could not grow that large.

But how about this one:

Paraceratherium is the largest land mammal known, larger than the largest species of mammoths (Mammuthus sungari, which may have approached it in size and weight). It is also known as the "giraffe rhinoceros". Adult Paraceratherium are estimated to have been 5.5 metres (18 ft) tall at the shoulder, 10 metres (33 ft) in length from nose to rump, a maximum raised head height of about 8 metres (26 ft), and a skull length of 1.5 metres (4.9 ft). Weight estimates vary greatly, but most realistic and reliable weight estimates are about 20(30) tonnes. This puts it in the weight range of some medium-sized sauropod dinosaurs.

Dinosaurs got bigger and bigger because their moms and dads made them eat their fruit & veg!

No. Seriously.....

They obviously grew bigger if it was advantageous to do so. Not every species of dinosaur would gain an advantage thru being larger, so not all species grew to an enormous size.

Humans are going the same way. Taller people are more successful, earn more money, and have more children. Therefore, every future generation will be bigger than the one before, until it becomes a disadvantage (or no advantage) to be larger.

There's no reason why we can't have 20-feet-tall ants in the future. It's just natural selection.

Share on other sites

Abramelin 2,499

Dinosaurs got bigger and bigger because their moms and dads made them eat their fruit & veg!

No. Seriously.....

They obviously grew bigger if it was advantageous to do so. Not every species of dinosaur would gain an advantage thru being larger, so not all species grew to an enormous size.

Humans are going the same way. Taller people are more successful, earn more money, and have more children. Therefore, every future generation will be bigger than the one before, until it becomes a disadvantage (or no advantage) to be larger.

There's no reason why we can't have 20-feet-tall ants in the future. It's just natural selection.

There appears to be a reason:

Atmospheric oxygen level and the evolution of insect body size.

Abstract

Insects are small relative to vertebrates, possibly owing to limitations or costs associated with their blind-ended tracheal respiratory system. The giant insects of the late Palaeozoic occurred when atmospheric PO(2) (aPO(2)) was hyperoxic, supporting a role for oxygen in the evolution of insect body size. The paucity of the insect fossil record and the complex interactions between atmospheric oxygen level, organisms and their communities makes it impossible to definitively accept or reject the historical oxygen-size link, and multiple alternative hypotheses exist. However, a variety of recent empirical findings support a link between oxygen and insect size, including: (i) most insects develop smaller body sizes in hypoxia, and some develop and evolve larger sizes in hyperoxia; (ii) insects developmentally and evolutionarily reduce their proportional investment in the tracheal system when living in higher aPO(2), suggesting that there are significant costs associated with tracheal system structure and function; and (iii) larger insects invest more of their body in the tracheal system, potentially leading to greater effects of aPO(2) on larger insects. Together, these provide a wealth of plausible mechanisms by which tracheal oxygen delivery may be centrally involved in setting the relatively small size of insects and for hyperoxia-enabled Palaeozoic gigantism.

Share this post

Link to post

Share on other sites

Kopernicus 0

The gigantism of dinosaurs was the result of a lowering of surface gravitation on the Earth. The Gravity Theory of Mass Extinction explains this as well as flood basalt volcanism (e.g. the Deccan Traps and Siberian Traps) and many other phenomena. If interested, go to www.dinoextinct.com and click on 'The Gravity Theory of Mass Extinction' to view the pdf.

Share this post

Link to post

Share on other sites

Fester John 0

Your all wrong... it was because the ozone layer was more than 200% thicker than it is now and fluctuates through time. Also there was an ice "shield" around the earth which in turn enhanced the effects of the ozone layer.. Ever think of where all that water came from that flooded the earth and killed the titans of old? Some core samples that are recovered from the poles give proof to this but would never be released to the public...

Insects are small relative to vertebrates, possibly owing to limitations or costs associated with their blind-ended tracheal respiratory system. The giant insects of the late Palaeozoic occurred when atmospheric PO(2) (aPO(2)) was hyperoxic, supporting a role for oxygen in the evolution of insect body size. The paucity of the insect fossil record and the complex interactions between atmospheric oxygen level, organisms and their communities makes it impossible to definitively accept or reject the historical oxygen-size link, and multiple alternative hypotheses exist. However, a variety of recent empirical findings support a link between oxygen and insect size, including: (i) most insects develop smaller body sizes in hypoxia, and some develop and evolve larger sizes in hyperoxia; (ii) insects developmentally and evolutionarily reduce their proportional investment in the tracheal system when living in higher aPO(2), suggesting that there are significant costs associated with tracheal system structure and function; and (iii) larger insects invest more of their body in the tracheal system, potentially leading to greater effects of aPO(2) on larger insects. Together, these provide a wealth of plausible mechanisms by which tracheal oxygen delivery may be centrally involved in setting the relatively small size of insects and for hyperoxia-enabled Palaeozoic gigantism.

Abramelin 2,499

Dinosars were in the Mesozoikum, the article by you posted talks about the Paleozoikum. Two different era's in earth history. And dinosaurs, are not insects ;-)

I know. It was just a reply to a remark about insects being able to grow to 20 feet... in the future. "Nothing" could hinder them to grow that large, but no, "something" would indeed hinder their gigantic growth.

Share this post

Link to post

Share on other sites

Abramelin 2,499

Your all wrong... it was because the ozone layer was more than 200% thicker than it is now and fluctuates through time. Also there was an ice "shield" around the earth which in turn enhanced the effects of the ozone layer.. Ever think of where all that water came from that flooded the earth and killed the titans of old? Some core samples that are recovered from the poles give proof to this but would never be released to the public...

Heh, I guess you read that somewhere. Care to share that source with us?

Share this post

Link to post

Share on other sites

Abramelin 2,499

The gigantism of dinosaurs was the result of a lowering of surface gravitation on the Earth. The Gravity Theory of Mass Extinction explains this as well as flood basalt volcanism (e.g. the Deccan Traps and Siberian Traps) and many other phenomena. If interested, go to www.dinoextinct.com and click on 'The Gravity Theory of Mass Extinction' to view the pdf.

Does that theory also explain this:

Look at the critter between the elephant and the T-rex.

Paraceratherium is the largest land mammal known, larger than the largest species of mammoths (Mammuthus sungari, which may have approached it in size and weight). It is also known as the "giraffe rhinoceros". Adult Paraceratherium are estimated to have been 5.5 metres (18 ft) tall at the shoulder, 10 metres (33 ft) in length from nose to rump, a maximum raised head height of about 8 metres (26 ft), and a skull length of 1.5 metres (4.9 ft). Weight estimates vary greatly, but most realistic and reliable weight estimates are about 20(30) tonnes. This puts it in the weight range of some medium-sized sauropod dinosaurs.

Share this post

Link to post

Share on other sites

Kopernicus 0

Paraceratherium is the largest land mammal known, larger than the largest species of mammoths (Mammuthus sungari, which may have approached it in size and weight). It is also known as the "giraffe rhinoceros". Adult Paraceratherium are estimated to have been 5.5 metres (18 ft) tall at the shoulder, 10 metres (33 ft) in length from nose to rump, a maximum raised head height of about 8 metres (26 ft), and a skull length of 1.5 metres (4.9 ft). Weight estimates vary greatly, but most realistic and reliable weight estimates are about 20(30) tonnes. This puts it in the weight range of some medium-sized sauropod dinosaurs.

Yes, the post K-T giant mammals, including Indricotherium, are explainable. The theory in the PDF cited posits that the surface gravity on Panagea varies depending on core element offset, which is determined by the movement of the center of mass (COM) of Pangea relative to the equator. At the K-T interval the COM of Pangea was rapidly moving toward the equator causing the major pulse of increasing gravitation and extinctions.

To account for Paraceratnerium and indricotherium, the COM of Pangea would have to have moved away from the equator relative to its position at the KT interval. The cited reference 'Plate Tectonics May Control Geomagnetic Rreversal Frequency' indicates that this happened. I have a copy of that PDF which was initially posted in November but disappeared shortly afterward, possibly for copyright reasons.